Estimation Of Constant Power Cycle Ergometer Work Rates Using Responses In Incremental Exercise Tests

The severe exercise intensity domain is defined as the range of work rates that is sustainable for ~2 to 30 minutes and will elicit maximal oxygen uptake (VO2max). Laboratory controlled study designs often require a more stringent timeframe (e.g. 10 - 14 minutes) for achieving VO2max, making selection of individualized work rates a challenging task. PURPOSE: This study aimed to develop a regression equation to predict cycle ergometer work rates that would elicit VO2max and result in fatigue in ~12 min (W12min). METHODS: Three women (mean ± SD, age, 23 ± 4 y; height, 168 ± 13 cm; body mass, 69 ± 18 kg) and six men (22 ± 2 y; 182 ± 8 cm; 79 ± 13 kg) performed incremental tests and severe intensity, constant power (range, 102 - 330 watts) tests on a cycle ergometer. Anthropometric measures, power output, and gas exchange data from the incremental tests were investigated as possible predictors of the dependent variable, W12min. Statistical analysis was performed to develop a W12min prediction model using a best-subsets regression method. RESULTS: Regression analysis revealed that absolute VO2 at the first ventilatory threshold (VT1), minute ventilation (VE) at the second ventilatory threshold (VT2), and peak power were significant predictors of W12min (R2 = 0.985, p < 0.001). W12min can be predicted using: W12min = 33.765 + 0.054(VO2 at VT1) - 1.859(VE at VT2) + 0.708(peak power). Variables are expressed in the following units: VO2 in mL·min-1; VE in BTPS L·min-1; peak power in watts. CONCLUSION: The regression analysis suggests that W12min can be predicted from the results of an incremental test by utilizing gas exchange variables and power outputs at the VTs and at the end of exercise. This has implications for any research laboratory evaluating responses in this domain with an intervention that alters duration (e.g. hypoxia or ergogenic aid) while still eliciting VO2max.